Proposed Mechanism:
Figure 7.10. Proposed mechanism. Taken from J. Inorg. Biochem., 105 ( 2), 127–141.
Catalase:
It is also a heme protein. It catalyzes disproportion of hydeogen peroxide to water and oxygen.
Active site:
In the active site of catalase iron is in +III oxidation state and it is in square pyramidal geometry where the basal plane is composed of four N atoms from the prophyrin ring and the fifth, i . e . the axial position is occupied by a tyrosine moiety.
Proposed mechanism:
Figure 7.11. Proposed mechanisms for the catalatic reaction. A , ionic mechanism by utilizing a general acid-base catalyst. B , radical mechanism. C , role of a general acid-base catalyst on the formation of compound I. Taken from JBC December 10, 2004 vol. 279 no. 50 52376-5238 .